ALEXANDRIA, Va. - After police found 16-year-old Jholie Moussa dead in a Fairfax County park, her mother says her life's mission will be to make sure there are changes to the way law enforcement investigate certain missing persons cases.

Two weeks later on Friday, investigators found Moussa dead under brush inside Woodlawn Park. The park sits less than a mile from Jholie's home where she was last seen on Jan. 12.

Steward-Hill is also asking for anyone with information about Moussa's death to come forward.

On Monday, a source with knowledge of the investigation told FOX 5 one of the last calls made to Moussa's cellphone came from the vicinity near the park where she was found dead. Family members had previously said an unidentified man borrowed a boy's phone and called Moussa. It is unclear if that man is a suspect of person of interest in the case.

Fairfax County police would not address questions Monday about how they handled the case. They have said previously that they did not fail to give Moussa's case proper attention. Police said at the time they did not have any information that contradicted the fact that she left her home willingly. Police have also stressed that nearly 500 people were reported as runaways last year, saying the resources don't exist to fully investigate every case.

Steward-Hill says she wants to work to make sure cases like her daughter's get more attention from law enforcement.

"It hurt me how it was handled," she said. "It just hurt because I know my child and I know that it was out of character for her not to come home."

Moussa's mother says the family shared several factors with police that contradicted their public statements that Moussa was a runaway, yet there was not sufficient information to issue an Amber Alert.

"The worst outcome that could possibly happen has happened, so at this point, I am in it for the long haul," said Steward-Hill. "I’m in it for the long haul because I don’t want anyone else to go through what my child went through."

Family members say there will be a public memorial service for Moussa on Thursday at 6 p.m. at New Life Open Bible Church in Springfield.